Induction apparatus



July 17, 1962 J. R. SMITH INDUCTION APPARATUS Filed April 16, 1956 u k m a 0m m .l/mm/ v m 4 4 m 5 V .0. 4 I w. m 9 \45 \9 4 m 3 6 .m 3 F 5m 1 m a F H 3 Kg A kg JE/ 9 3 I 4 H .4

United States Patent 3,045,195 INDUCTION APPARATUS John R. Smith, Venetia, Pa., assignor to McGraw-Edison Company, a corporation of Delaware Filed Apr. 16, 1956, Ser. No. 578,450 1 Claim. (Cl. 33660) This invention relates to induction apparatus and is particularly directed to an induction apparatus which may be relatively heavily loaded and yet will remain at a temperature far below the destructive or damaging temperature.

The induction apparatus may be a transformer, a choke, or any other type of induction apparatus with or without a magnetic core.

The primary object of this invention is to provide a novel form of winding construction for the induction apparatus in which each convolution projects axially beyond the adjacent convolution and thus provides an exposed surface for each convolution which is directly contacted by the flowing and cooling dielectric.

' Further objects of the invention are to provide a simple type of construction which does not require the use of additional apparatus and does not increase the over all cost of the induction apparatus and which is easy to produce and highly efficient in operation.

Embodiments of the invention are shown in the accompanying drawings in which:

FIGURE 1 is a fragmentary transverse sectional view through a transformer.

FIGURE 2 is a side elevation drawn to a much reduced scale.

FIGURE 3 is a view of a fragment of the transformer showing in section the winding construction.

FIGURE 4 is a view corresponding to FIGURE 3 showing a further form of the invention.

FIGURE 5 is a view similar to FIGURE 3 but showing insulating spacers in their relative position with respect to the winding.

FIGURE 6 is a fragmentary view of one of the spacers.

Referring to the drawings particularly FIGURES l, 2 and 3 it will be seen from FIGURE 1 that the induction apparatus chosen for illustration is a transformer though this invention is applicable to chokes or other forms of induction apparatus with or without magnetic cores. The invention, however, is particularly useful in transformer constructions where the transformer is enclosed in a casing or tank.

In FIGURE 1 a laminated magnetic core of cruciform cross section is indicated by the reference character 1. Surrounding this core are the windings 2 and 3 which may be the primary and secondary windings or vice versa. However, the construction has been shown with the windings 3 of aheavy conducting strip of rectangular cross section indicated by the reference character 4, the winding as a whole being indicated by the reference character 3 in FIGURES 1 and 3 and the two windings primary and secondary being indicated generally by the reference character 5 in FIGURE 2. This invention is applicable to any other type of conducting winding or conducting windings.

A metal casing 6 surrounds the transformer and contains a dielectric whose upper level is shown in FIGURE 2 and is indicated by the reference character 7. i

It is usual to provide some means for circulating the dielectric, such as oil for instance, and for cooling the dielectric externally of the casing 6. For example, the cooling or radiating pipes 8 may be provided which open into the upper and lower portions of the casing 6. This provides a natural or gravity flow of dielectric externally of the casing, the hot dielectric passing into the upper charged into the lower portion of the casing. Any other customary or usual type of external cooling of the dielectric may be employed.

This invention is particularly directed to the cooling of the winding means whether it be a single winding or a multiplicity of windings.

FIGURE 3 shows one arrangement of the conducting winding. It will be noted that the conducting winding is made up of a series of pancake coils which, as may be seen from FIGURE 5, are spaced apart by any suitable dielectric strips or spacers 9 which interlock with vertical spacers 10 in the usual manner. The winding 3, it will be seen, consists of spaced pancake windings so that the dielectric fluid can flow freely upwardly between successive pancake coils.

Each successive convolution of the conductors 4 are stepped upwardly so as to provide a series of exposed surfaces indicated by the reference character 11. These exposed surfaces are directly contacted by the dielectric and greatly enhance the cooling effect of the dielectric. The successive convolutions are insulated from each other in any suitable manner. For example, the conductor 4 may be wrapped with kraft paper or other suitable insulating material which is permeable to the dielectric.

It is to be particularly noted that the rectangular conductor is arranged with its longer face vertical and its shorter face horizontal. This facilitates the arrangement of the successive projecting portions or faces 11 of the winding 4 as shown in FIGURE 3.

It has been found that the cooling effect is increased by approximately 15% over the usual pancake form of coil, whether this pancake coil is dished or flat. However, by using the dished form with each of the successive convolutions projecting beyond the upper edge of the adjacent convolution this additional exposed cooling surface is obtained.

It is obvious that the successive pancake windings may project upwardly as the center of the pancake winding is approached as shown in FIGURE 3, or may project downwardly as shown in FIGURE 4 as the center of the winding is approached,

As shown in FIGURE 4 the conducting winding is indicated by the reference character 4. FIGURE 4 differs from FIGURE 3 only in that the pancake winding is dished downwardly in FIGURE 4 whereas in FIGURE 3 it is dished upwardly.

No attempt has been made to show the insulating and mechanical structure of the transformer in detail as the invention is directed primarily to the peculiar and novel way in which the additional cooling is obtained.

In actual tests a conducting winding having the Vertical dimension of .325 inch and a horizontal of .091 inch was employed. This particular construction showed an actual increase in efliciency in cooling of from 10% to 15% as compared with a similar winding in which no exposed vertical surface was provided for each successive convolution of the conducting winding.

Any suitable means may be employed for constructing the conducting winding. For instance, the pancake coils may be wound flat with the spacers in place and may be subsequently dished by placing a suitable former below the winding and forcing the winding against such former. Or if desired the dished pancake windings may be formed while the winding is taking place.

It is obvious that other forms of radiators could be provided for cooling the dielectric and other forms of induction apparatus could be employed as the invention is not limited solely to the particular form illustrated, nor is it limited to the particular way in which the dielectric is cooled. However, the invention is directed as herein- J above set forth to the Peculiar construction whereby the increase in cooling is obtained.

It is to be noted particularly that the pancake windings do not obstruct the flow of oil or other dielectric but assist in the upward flow of the oil as each pancake winding heats the oil and directs it upwardly. Also it is to be noted that the pancake coils are not enclosed as units. Each individual convoluting projects beyond the adjacent convolution and is directly exposed to the upwardly flowing cooling dielectric.

In other words, the dished arrangement of each pancake coil causes each pancake coil to have a chimney action in addition to the general upward fiow of the main body of the oil. The dished shape of the pancake coil provides guiding, upwardly inclined, surface which augment the upward flow of the oil. It is to be noted that for each individual pancake coil that heat is transmitted to the oil at vertically spaced points throughout the entire vertical height of the pancake coil itself. This effect is immediately apparent when the dished pancake coil of this invention is contrasted with a. horizontally arranged pancake coil. In the horizontally arranged pancake coil construction there would be no upward flow of oil except the general upward flow of the whole body of the oil. In the present invention the upward flow of the main body of the oil is materially augmented by the individual action of each pancake coil as described immediately hereinabove.

It is intended that the term fluid shall be understood to cover either a liquid or a gas. In addition, it is to be understood that forced circulation of oil in the tank could be employed.

It will be seen that a novel form of induction apparatus has been provided in which the cooling eifect is greatly enhanced by following the invention hereinabove set forth.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

1 claim:

An induction apparatus for use as a transformer having a magnetic core structure and a conducting winding surrounding said core structure, said winding consisting of conductor means having a rectangular cross section wound spirally in spaced layers with the successive conductors of each layer in substantial contact with each other and with successive convolutions in the several layers arranged in partially overlapping relation to adjacent convolutions and having a portion of each of said successive convolutions projecting beyond the adjacent convolution measured axially of the winding, said winding forming a substantially rigid structure, and a cooling medium in which the winding is immersed, said cooling medium contacting the end faces and the side faces of said projecting portions and flowing from one face to a successive face of the convolutions of each layer to thereby enhance the cooling effect of the cooling medium.

References Cited in the file of this patent UNITED STATES PATENTS 1,145,366 Herrold July 6, 1915 1,183,616 Wooldridge May 16, 1916 1,984,996 Sauer Dec. 18, 1934 2,479,373 Knotts et al Aug. 16, 1949 2,751,562 Camilli et al. June 19, 1956 2,831,173 Whiteman Apr. 15, 1958 

